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Background-The association between higher body mass index (BMI) and lower B-type natriuretic peptide (BNP) level is thought to be mediated by expression of the natriuretic peptide clearance receptor (NPR-C) in adipose tissue. To explore this association, we tested 2 hypotheses: (1) that N-terminal (NT)-proBNP, which is not believed to bind NPR-C, would not be associated with BMI and (2) that lower BNP would be more closely associated with fat mass than with lean mass. Methods and Results-Measurements of BNP, NT-proBNP, and body composition by direct dual energy x-ray absorptiometry (DEXA) were performed in 2707 subjects from the Dallas Heart Study. The associations between obesity and low BNP (Ͻ4 ng/L) or low NT-proBNP (lowest sex-specific quartile) were evaluated with multivariable logistic regression models stratified by sex and adjusted for age, race/ethnicity, hypertension, left ventricular mass, and end-diastolic volume. Higher BMI was independently associated with lower BNP and NT-proBNP (all PϽ0.001). When BMI was replaced with both DEXA-derived lean and fat mass, greater lean mass, but not fat mass, was associated with low BNP and NT-proBNP levels. Conclusions-In a large, population-based cohort, we confirm the previously described association between higher BMIand lower BNP and demonstrate a similar inverse association between BMI and NT-proBNP. Interestingly, both BNP and NT-proBNP are more closely associated with lean mass than with fat mass. These findings do not support the hypothesis that the lower BNP levels seen in obesity are driven by enhanced BNP clearance mediated via NPR-C.

Background-Although gender-specific criteria are common for defining cardiac traits such as left ventricular hypertrophy, left ventricular ejection fraction (LVEF) thresholds widely used in clinical practice have traditionally been the same for women and men, perhaps because it remains uncertain whether there is a systematic difference in LVEF between genders. Methods and Results-Using cardiac magnetic resonance imaging in a probability-based sample of Dallas County residents aged 30 to 65 years (1435 women and 1183 men), we compared LVEF in women and men. The association of gender with stroke volume independent of end-diastolic volume (EDV) or other potential confounders was assessed by multivariable analysis. Gender-specific thresholds for a low LVEF were defined at the 2.5th percentile in women and men from a healthy reference subpopulation. The median (25th, 75th percentile) LVEF was higher in women than in men (75% [70%, 79%] in women versus 70% [65%, 75%] in men, PϽ0.001). Left ventricular EDV and end-systolic volume indexed to body surface area were smaller in women than in men (PϽ0.001 for both). Gender remained significantly associated with stroke volume, independent of EDV and other potential confounders in multivariable analysis. A low LVEF was defined as below 61% in women and below 55% in men. Conclusions-Women have a higher LVEF than men in the general population, secondary to a higher stroke volume for a given EDV independent of known potential confounders.

Plate 1. Surface-rendered projections of statistical maps reflecting activation during (1a) generative writing of words versus repetitive drawing of circles; (1b) generative writing of words versus writing letters of the alphabet; (1c) writing letters of the alphabet versus repetitive drawing of circles; (1d) generative writing of words versus generative subvocal naming of words. Display threshold set at T = 4.02 (uncorrected p < .001; extent threshold 50 voxels). Plate 2. Coronal and axial sections showing activation in the posterior inferior temporal lobe (white arrows), superior parietal region (pink arrows), and Exner's area (green arrows) for the contrasts: (2a) generative writing of words versus repetitive drawing of circles; (2b) generative writing of words versus writing letters of the alphabet; (2c) writing letters of the alphabet versus repetitive drawing of circles. Display threshold set at T = 4.02 (uncorrected p < .001; extent threshold 50 voxels). Plate 3. Sagittal sections showing results of region of interest analysis in the left inferior temporo-occipital region for the contrasts: (3a) generative writing of words versus repetitive drawing of circles; (3b) generative writing of words versus writing letters of the alphabet; (3c) writing letters of the alphabet versus repetitive drawing of circles;(3d) written naming versus generative subvocal naming. Functional magnetic resonance imaging was used with 12 adults to examine activation associated with generative writing of words from semantic categories contrasted with writing letters of the alphabet and drawing circles. In addition, the generative writing condition was contrasted with a subvocal generative naming condition.Outcomes & Results: Semantically guided retrieval of orthographic word forms for the generative writing condition revealed activation in the left inferior and dorsolateral prefrontal cortex, as well as the left posterior inferior temporal lobe (BA 37). However, no activation was detected in the left angular gyrus (BA 39). The motor components of writing were associated with activation in left fronto-parietal cortex including the region of the intraparietal sulcus, superior parietal lobule, dorsolateral and medial premotor cortex, and sensorimotor areas for the hand.

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